ONE THING needs to be well understood by disaffected Philippine soldiers, would-be juntas and the friends of Sen. Juan Ponce Enrile: their repeated attempts to capsize the legal government of the Philippines are regarded as acts of political vandalism by most of the world. Had this latest attempt succeeded, most other countries -- including this one -- would have regarded it as criminal and treated it accordingly. Some of the coup-makers had evidently persuaded themselves that because they claim to be fervently anticommunist, conservative governments abroad would receive them with sympathy. That was a gross mistake. The crucial distinction is that President Corazon Aquino's government is a genuine democracy, while the coup-makers have something quite different in mind. When the fighting broke out early Friday, President Reagan immediately and forcefully warned them that his support for Mrs. Aquino is unqualified. They would be wise to take him at his word.

The attacks on Friday were the fifth attempt at a coup since Mrs. Aquino came to power 18 months ago. Some of the others were pretty inept affairs, and the government was lenient in dealing with the leaders -- perhaps mistakenly. This latest affair was much more violent and bloody. Mrs. Aquino will no longer be able to let it pass. This time too many people died.

When Mr. Enrile took his seat as an elected senator two weeks ago, a lot of people in the Philippines took that as a very good sign. It meant, they thought, that the probability of further military subversion had declined and that the opposition to Mrs. Aquino had turned to constitutional and parliamentary methods. But Mr. Enrile is a man who changes sides easily and remorselessly.

As defense minister under the departed Ferdinand Marcos, he played a large part in the revolution in early 1986 when he swung to Mrs. Aquino's side. She rewarded him by making him her own defense minister -- until, last November, his connection to a succession of plots had become too close for any president to tolerate. His relationship to the most recent assault is not yet clear, but its nominal leader is one of his close associates.

While the government's enemies have made themselves felt in these past two days, it demonstrably has many friends as well. Most of the army are thought to remain absolutely loyal to it, as well as most of the population. That's another reason why these repeated attempts by a small minority to subvert the new government deserve the world's contempt.